Persistent endothelial dysfunction in post-COVID-19 syndrome and its associations with symptom severity and chronic inflammation (preprint)

Background Post-COVID-19 syndrome (PCS) is a lingering disease with ongoing symptoms such as fatigue and cognitive impairment resulting in a high impact on the daily life of patients. Understanding the pathophysiology of PCS is a public health priority, as it still poses a diagnostic and treatment challenge for physicians. Methods In this prospective observational cohort study, we analyzed the retinal microcirculation using Retinal Vessel Analysis (RVA) in a cohort of patients with PCS and compared it to an age- and gender-matched healthy cohort (n=41, matched out of n = 204). Measurements and main results PCS patients exhibit persistent endothelial dysfunction (ED), as indicated by significantly lower venular flicker-induced dilation (vmax; 3.42% ± 1.77% vs. 4.64 % ± 2.59%; p = 0.02), narrower central retinal artery equivalent (CRAE; 178.1 [167.5 - 190.2] vs. 189.1 [179.4 - 197.2], p = 0.01) and lower arteriolar-venular ratio (AVR; (0.84 [0.8 - 0.9] vs. 0.88 [0.8 - 0.9], p = 0.007). When combining AVR and vmax, predicted scores reached good ability to discriminate groups (area under the curve: 0.75). Higher PCS severity scores correlated with lower AVR (R= -0.37 p = 0.017). The association of microvascular changes with PCS severity were amplified in PCS patients exhibiting higher levels of inflammatory parameters. Conclusion Our results demonstrate that prolonged endothelial dysfunction is a hallmark of PCS, and impairments of the microcirculation seem to explain ongoing symptoms in patients. As potential therapies for PCS emerge, RVA parameters may become relevant as clinical biomarkers for diagnosis and therapy management. Trial Registration This study was previously registered at ClinicalTrials (“All Eyes on PCS - Analysis of the Retinal Microvasculature in Patients With Post-COVID-19 Syndrome”. NCT05635552. https://clinicaltrials.gov/ct2/show/NCT05635552).

Longitudinal SARS-CoV-2 neutralization of Omicron BA.1, BA.5 and BQ.1.1 after four vaccinations and the impact of break-through infections in hemodialysis patients (preprint)

Background Individuals on hemodialysis are more vulnerable to SARS-CoV-2 infection than the general population due to end-stage kidney disease-induced immunosuppression. Methods 26 hemodialysis patients experiencing SARS-CoV-2 infection after 3rd vaccination were matched 1:1 to 26 out of 92 SARS-CoV-2 naives by age, sex, dialysis vintage and immunosuppressive drugs receiving a 4th vaccination with an mRNA-based vaccine. A competitive surrogate neutralization assay was used to monitor vaccination success. To determine infection neutralization titers, Vero-E6 cells were infected with SARS-CoV-2 variants of concern (VoC), Omicron sub-lineage BA.1, BA.5, and BQ.1.1. 50% inhibitory concentration (IC50, serum dilution factor 1:x) was determined before, four weeks after and 6 months after the 4th vaccination. Results 52 hemodialysis patients received four COVID-19 vaccinations and were followed up for a median of 6.3 months. Patient characteristics did not differ between the matched cohorts. Patients without a SARS-CoV-2 infection had a significant reduction of real virus neutralization capacity for all Omicron sub-lineages after six months (p<0.001 each). Those patients with a virus infection did not experience a reduction of real virus neutralization capacity after six months. Compared to the other Omicron VoC the BQ.1.1 sub-lineage had the lowest virus neutralization capacity. Conclusions SARS-CoV-2-naive hemodialysis patients had significantly decreased virus neutralization capacity six months after the 4th vaccination whereas patients with a SARS-CoV-2 infection had no change in neutralization capacity. This was independent of age, sex, dialysis vintage and immunosuppression. Therefore, in infection-naive hemodialysis patients a fifth COVID-19 vaccination might be reasonable 6 months after the 4th vaccination.

Improved SARS-CoV-2 neutralization of Delta and Omicron variants of concern after fourth vaccination in hemodialysis patients (preprint)

Background Hemodialysis patients are exposed to a markedly increased risk when infected with SARS-CoV-2. To date it is unclear if hemodialysis patients benefit from a fourth vaccination. Methods A total of 142 hemodialysis patients (median age 72.6 years, 33.8% female) received four COVID-19 vaccinations between December 2020 and March 2022. RDB binding antibody titers were determined in a competitive surrogate neutralization assay. Vero-E6 cells were infected with SARS-CoV-2 variants of concern (VoC) Delta (B.1.617.2) or Omicron (B.1.1.529, sub lineage BA.1) in a biosafety level 3 laboratory to determine serum infection neutralization capacity before and after vaccination. Results After the fourth vaccination serum infection neutralization capacity significantly increased from a 50% inhibitory concentration (IC50, serum dilution factor 1:x) of 247.0 (46.3-1560.8) to 2560.0 (1174.0-2560.0) for the Delta VoC, and from 37.5 (20.0-198.8) to 668.5 (182.2-2560.0) for the Omicron VoC (each p<0.001). A significant increase of the neutralization capacity was even observed for patients who had high antibody titers after three vaccinations (p<0.001). Univariate regression analysis indicated immunosuppressive medication (p=0.001) and hepatitis B vaccination non-response (p=0.046), and multivariate analysis immunosuppressive medication as the only factor associated with a reduced effect against Delta (p<0.001). Ten patients with SARS-CoV-2 breakthrough infection before the fourth vaccination had by trend lower prior neutralization capacity for Omicron (p=0.051). Conclusions Our findings suggest that hemodialysis patients benefit from a fourth vaccination in particular in the light of the highly infectious SARS-CoV-2 Omicron variant. A routinely applied four-time vaccination seems to broaden immunity against variants and would be recommended in hemodialysis patients.

Development and Validation of a Simplified Risk Score for the Prediction of Critical COVID-19 Illness in Newly Diagnosed Patients (preprint)

Scores for identifying patients at high risk of progression of the coronavirus disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), are discussed as key instruments for clinical decision-making and patient management during the current pandemic. Here we used the patient data from the multicenter Lean European Open Survey on SARS-CoV-2 - Infected Patients (LEOSS) and applied a technique of variable selection in order to develop a simplified score to identify patients at increased risk of critical illness or death. A total of 1,946 patients, who were tested positive for SARS-CoV-2 were included in the initial analysis. They were split into a derivation and a validation cohort (n=1,297 and 649, respectively). A stability selection among a total of 105 baseline predictors for the combined endpoint of progression to critical phase or COVID-19-related death allowed us to develop a simplified score consisting of five predictors: CRP, Age, clinical disease phase (uncomplicated vs. complicated), serum urea and D-dimer (abbreviated as CAPS-D score). This score showed an AUC of 0.81 (CI95%: 0.77-0.85) in the validation cohort for predicting the combined endpoint within 7 days of diagnosis and 0.81 (CI95%: 0.77-0.85) during the full follow-up. Finally, we used an additional prospective cohort of 682 patients, who were diagnosed largely after the “first wave” of the pandemic to validate predictive accuracy of the score, observing similar results (AUC for an event within 7 days: 0.83, CI95%, 0.78-0.87; for full follow-up: 0.82, CI95%, 0.78-0.86). We thus successfully establish and validate an easily applicable score to calculate the risk of disease progression of COVID-19 to critical illness or death.

Cytokine release syndrome is not usually caused by secondary hemophagocytic lymphohistiocytosis in a cohort of 19 critically ill COVID-19 patients (preprint)

Background: Severe COVID-19 associated respiratory failure, poses the one challenge of our days. Assessment and treatment of COVID-19 associated hyperinflammation may be key to improve outcomes. It was speculated that in subgroups of patients secondary hemophagocytic lymphohistiocytosis (sHLH) or cytokine release syndrome (CRS) with features of macrophage activation syndrome might drive severe disease trajectories. If confirmed, profound immunosuppressive therapy would be a rationale treatment approach.Methods: Over a median observation period of 11 (IQR: 8; 16) days, 19 consecutive confirmed severe COVID-19-patients admitted to our intensive-care-unit were tested for presence of sHLH by two independent experts. HScores and 2004-HLH diagnostic criteria were assessed. Patients were grouped according to short-term clinical courses: discharge from ICU versus ongoing ARDS or death at time of analysis.Results: The median HScore at admission was 157 (IQR: 98;180), without the key clinical triad of HLH, i.e. progressive cytopenia, persistent fever and organomegaly. Independent expert chart review revealed the absence of sHLH in all cases. No patient reached more than 3/6 of modified HLH 2004 criteria. Nevertheless, patients presented hyperinflammation with peripheral neutrophilic signatures (neutrophil/lymphocyte-ratio>3.5). The latter best paralleled their short-term clinical courses, with declining relative neutrophil numbers prior to extubation (4.4, [IQR: 2.5;6.3]; n=8) versus those with unfavourable courses (7.6, [IQR: 5.2;31], n=9).Conclusion: Our study rules out virus induced sHLH as the leading cause of most severe-COVID-19 trajectories. Instead, an associated innate neutrophilic hyperinflammatory response or virus-associated-CRS appears dominant in patients with an unfavourable clinical course. Therapeutic implications are discussed.